In the hydraulic art, the techniques of shimming control valve spools and relief valve springs has long existed. In certain directional control valve applications, it is necessary that the valve spool pass a specific flow rate in a certain position. Due to the various tolerances in the spool and valve body, it is quite often necessary to shim so that at a certain position of the spool, the flow rate is in accordance with the design parameters of the valve. To achieve this in the past, the valve had to be disassembled once on a test stand and shims added. The valve was then checked for a second time to insure the proper flow rate, all of which is very time-consuming and expensive.
With the present invention, the spool stop is formed by an end plug which is formed of a relatively soft material. The plug is screwed into the valve body causing the contact points on the plug to deform above their elastic limit to a point where the designed flow rate is set. This avoids the necessity of removing the plug and inserting shims. In addition, the plug of the present invention may be removed in the field after it has been set at the factory, and reinstalled to a lower factory-recommended torque value which will return the plug within tolerance levels of its original setting, since this lower torque value will not cause the deformed portion of the plug to exceed the elastic limit.
It is therefore the principal object of the present invention to provide a valve spool end plug having deformable contact points for setting the spool flow rates, which plug can be removed and reinstalled in the field while retaining factory settings within original tolerance levels.
Another object of the present invention is to provide a deformable plug which functions as a variable size shim to vary spring loadings on relief valves or valve spool positions.
Other features and advantages of the present invention will become more apparent from the following description, appended claims and drawings.